Thermostat



Sept. 16, 1930. A. GRAUE 1,775,900

THERMOS TAT Filed March 5, 1928 2 Sheets-Sheet l INVENTOR E IEYLG :LL. ARNO 694115. 4 BY A TTOR NE Y5.

A. GRAUE THERMOSTAT Sept. 16, 1930.

Filed March 5, 1928 2 Sheets-Sheet 2 INVENTOR. ARNG GRAVE- f 1/0 Vol.7:

A TTOR NE Y5.

Patented Sept. 16, 1930 PATENT OFFICE AIR-NO GRAUE, OF SAN FRANCISCO, CALIFORNIA THERMOSTAT Application filed March 5,

The present invention relates to improvements in thermostats, and its principal object is to provide a thermostat adapted for temperature control that is particularly efii- F cient for its purposes.

Moreover, it is proposed to utilize a pendulum allowing one or more heat responsive elements to act thereon for the purpose of bringing about certain results as, for instance, the closing of an electrical circuit.

It is further proposed to render the device particularly eflicient by allowing its heat responsive elements to act on the pendulum on opposite sides of its support, whereby the sensitiveness of the thermostat is increased.

It is further proposed to provide indicating means in connection with the pendulum which allow the temperatureto be read from a dial.

A further object of the invention is to provide two circuits in connection with the pendulum, one having a heating device and the other a cooling deviceassociated therewith, and one circuit being rendered active when the pendulum swings in one direction beyond a predetermined point while the other circuit is rendered active when the pendulum swings in the opposite direction beyond a predetermined point, and both' circuits being arranged so as not to impede the progress of the pendulum after the latter has acted on the circuits.

It is further intended for the purpose of increasing the efliciency and responsiveness of the device to include relays in the Various circuits which allow the contacts to come together and to part quickly whenever a circuit is closed or opened by my apparatus.

It is further proposed to connect an alarm circuit with my thermostat which is rendered active when the temperature exceeds a predetermined higher degree.

Further objects and advantages of my invention will appear as the specification proceeds.

1928. Serial No. 259,213.

mostat with the scale plate of Figure 4 removed;

Figure 2 a section taken along line II-II of Figure 1;

Figure 3 a horizontal section taken along line IIIIII of Figure 1;

Figure 4 a front view of adial as seen from line IVIV of Figure 2;

Figure 5 a wiring diagram; and

Figure 6 a front View of a modified form of operating mechanism for my thermostat.

While I have shown only two preferred forms of my invention, I wish to have it understood that various changes or modifications may be made within the scope of the claims hereto attached without departing from the spirit of the invention.

In the form shown in Figures 14 a supporting bar 1 is fastened in spaced relation to the backing 2 through insulating blocks 3. To the upper end of the bar is pivoted as shown at 4 a pendulum 6, which latter is acted on by two heat responsive elements 7 engaging the pendulum on opposite sides of its support 4 as shown at 8. In the form shown in Figure 1, each of the heat responsive elements comprises two blades 9 and 11 made of materials of different coefiicicnt of expansion such as copper and invar, and bent into substantially circular form with one end fastened to the bar 1 as shown at 12, while the other end has a bar 13 extending therefrom in substantially parallel relation to the bar 1. The upper end of the bar 13 has a spring 14 fastened thereto the tension of which may be adjusted by means of a screw 16, and which carries at its upper end a pin 17 pivotally engaging the pendulum as at 8. Ample play is preferably provided between the pins 17 and the pendulum by enlargement of the holes 18 in the pendulum in the manner shown in the drawing.

The lower end of the pendulum has a short shaft 19 extending therefrom, which latter shaft carries a pointer 21 adapted to move over the dial 22 shown in detail in Figure 4 for indicating the prevailing temperature. In order to prevent the pendulum from being injured, particularly during shipping and other handling of the device, I provide a fixed guide member 23 on the back of the dial 22 and a grooved Wheel 24 on the shaft 19 arranged in close proximity to the guide 23. This wheel normally does not touch the guide 23 but is held thereby against movement outside of the plane of the guide whereby bending of the pendulum is prevented.

The lower extremity of the pendulum has a finger 26 extending downwardly therefrom, which latter finger serves to render operative either a heating circuit or a cooling circuit when the pendulum swings beyond a predetermined point due to changes in temperature. The two sides of the arrangement responsive to the movement of the pendu lum in one direction or the other are identical in construction, and the description will therefore be confined to one.

Two solenoids 27 and 28 are mounted transversely to the path of the pendulum, and their plungers 29 and 30 are interconnected by a lever 31, which latter is fulcrumed between the two plungers as at 32. The lever has two arms 33 and 34 extending from the ends thereof toward the pendulum, and the front arm carries on an insulating block 36 a contact 37, which latter is arranged to normally lie in the path of the finger 26 of the pendulum. The arm 33 has also depending therefrom a leg 38 terminating in a contact 39 adapted to engage with a stationary contact 41 for closing a circuit. The arm 33 of the lever is heavier than the arm 34 or is held under spring pressure so that when left free to operate it will close the contacts 39 and 41.

Normally, the plunger 30, and with it the arm 33, is held in the raised position by means of a latch 42 mounted underneath the two solenoids and extending for a short distance under the plunger 30 so as to hold the same. The latch itself is held in locking position by the second plunger 29 abutting against the rear end of the latch, while a spring 43 tends to withdraw the latch from its locking position. The plunger 30 is made in two pieces 44 and 46 interconnected by means ofapin 47 threaded into the upper piece 44 and slidable in the lower piece 46, while a spring 48 encircling the pin tends to separate the two parts 44 and 46. It thus appears that when the solenoid 28 is energized due to the finger 26 of the pendulum striking the contact 37 on the front lever arm, the upper part 44 of the solenoid is first drawn downward, compressing the spring 48, whereby the plunger 29 is pulled upward sufliciently to release the latch 42 which is drawn backward by the spring 43 and thereby releases the lower part 46 of the plunger and allows the entire plunger 30 to proceed in its downward course for engaging the contact 39 with the contact 41 for closing the heating or cooling circuit as the case may be.

An arm 49 is pivoted to the rear wall as shown at 51 and is supported by a pin 52 extending sideway from a forward extension 53 of the rear arm 34 of the lever 31. When the rear arm 34 is in its lowermost position, as shown in the drawing, the arm 49 supported by its pin 52 is below the reach of-the pendulum, but when the arm 34 is raised due to the energizing of the front solenoid 28, the arm 49 is raised also into the path of the pendulum so that the latter strikes a contact 54 mounted on the front end of the arm 49 on its return movement. When the finger on the pendulum strikes this contact, it closes a circuit energizing the solenoid 27, which again reverses the position of the lever 31 and brings all the parts back to their original position.

The operation of my device will best be understood by reference to the wiring dia gram of Figure 5, from which it appears that the contact 26 is connected through the wire 56 with one side 57 of a six-volt line, which may be connected to either a battery or a transformer with a rectifier, while the contact 37 is connected through the windings of the solenoid 28 and the wires 58 and 59 to the other side 61 of the six-volt line. The contact 54 on the arm 49 is connected through the wire 62, the winding of the solenoid 27, and the wires 63, 58 and 59 to one side of the six-volt line. The contacts 39 and 41 form part of a 110 volt circuit, which may contain an electrical fan as indicated at 64 or an electrical stove as indicated at 66.

In operation, as the pendulum swings to the left as viewed in Figure 5 and reaches a predetermined temperature, for instance 80 on the scale shown in Figure 4, its finger 26 contacts the contact 37 and closes the lower voltage circuit, including the wire 56, the

contacts 26 and 37, the solenoid 28, and the wires 58 and 59. This energizes the solenoid 28 and causes the plunger part 44 to move downward, compressing the spring 48 and releasing the latch 42, whereupon the entire plunger of the front solenoid moves downward, with the result that the solenoid circuit is opened again due to the downward travel of the contact 37 while the high voltage fan circuit is closed due to the engagement of the contact 39 with the contact 41. Hereby the fan is set in motion and the temperature decreases so that the pendulum begins to swing backward. On its backward motion it strikes the contact 54 which has been raised into its path by the raising of the rear arm 34 of the lever 31. Thereby the pendulum closes the circuit comprising the wire 56, the contacts 26 and 54, the wire 62, the winding of the solenoid 27, and the wires 63, 58 and 59. The energizing of the solenoid 27 brings down the second plunger 29 and re moves the contact 54 immediately from the path of the pendulum so that the latter is free to move onward immediately upon striking the contact 54. The downward movement of the plunger 29 effects an upward movement of the plunger 30, thereby returning all the elements to their original po sition and opening the high voltage circuit controlled by the contacts 39 and 41 so that the fan stops operating. a

It should be remarked that the rear plunger 29 on its downward motion strikes the rear end of the latch 42 with its curved bottom and causes the latch to advance to form a lock for the plunger 30. It should be understood in this connection that the pivotal joints between the lever 31 and the lungers are sufliciently loose to compensate or the differences in movement and to allow the lower part 46 of the plunger 30 to clear the latch while its rear end is struck b the rear plunger. The front end of the latch is preferably rounded to facilitate its operation.

I also preferably use an alarm device adapted to become operative at extremely high temperatures, and for this pur ose I provide two contacts 67 and 68, the ormer being adjustable by means of a screw 69 and the latter being mounted on a spring adapted to be moved toward the former contact by a member 71 adjustably fastened as shown at 7 2 to the pendulum 6 when the temperature rises to anextremely high degree.

In the modified form of Figure 6 a different heat responsive means is used for operating the pendulum. The base or backing 7 6 is an elongated casting made of heat responsive material such as brass or aluminum, and is characterized by a straight rib 7 7 extending throughout the length thereof. Two springs 7 8 of invar are fastened on opposite sides so as to be under tension, and means are provided in allowing the tension to be adjusted by means of set screws 79 bearing upon the upper ends of the two springs, which latter are held to the metal rib by means of screws 81 adapted to ride in slots 82. The pendulum 84: is operated on opposite sides of its supporting point 86 by means of levers 87 fulcrumed in lugs 88 projecting from the metal rib in opposite directions. Lugs 89 extending from the centers of the springs operate the lower ends of the two levers 87, and motion is transmitted to the pendulum 84 by means of connecting links 91. Apart from the method of operating the pendulum, this form offers no difference over that disclosed in Figures 1-4.

I claim:

1. In a thermostat control, a pendulum, means for suspending the same, heat responsive means active on the pendulum for swinging the same in response to changes in temperature, an electric circuit, and electro-magnetic means causing the pendulum to close said circuit at a predetermined point of its swinging motion, the said means being constructed to clear the path of the pendulum for further swinging motion, after the pendu lum has acted on the same.

2. In a thermostat control, a pendulum, means for suspending the same, heat responsive means active on the pendulum for swinging the same in response to changes in temperature, an electric circuit, and electro-magnetic means causing the pendulum to close said circuit at a predetermined point of its swinging motion, the said means being constructed to clear the path of the pendulum for further swinging motion after the pendulum has acted on the same, and having means associated therewith allowing the pendulum to open the circuit on its return motion.

3. In a thermostat control, a pendulum, means for suspending the same, means for swinging the pendulum in response to temperature changes, an electric circuit, two solenoids mounted relative to the pendulum, a lever pivoted to the plungers of the solenoids for rocking motion having a contact associated with one arm thereof extending normally into the path of the pendulum so as to be contacted thereby for energizing one of the solenoids whereby the plunger of said solenoid is moved for rocking the lever and for withdrawing the contact from the path of the pendulum, means causing said lever to simultaneously close the circuit, and a second contact for the second solenoid, operatively connected with the other lever arm for proection into the return path of the pendulum by the same lever action and ada ted to be contacted by the returning pen ulum for energ zing the second solenoid whereby the lever 1s rocked in an opposite sense and returned to its original position.

4 In a control device of the character described, two solenoids, a lever connecting the plungers thereof, a latch for one of the plungers, means allowing the other plunger to move the latch into locking position and to hold it there, and yielding means embod ed 1n the first plunger allowing of slight initial movement thereof for ermitting the second plunger to withdraw rom its latchholding position.

5. In a thermostat control, a pendulum, means for suspending the same, heat responsive means active on the pendulum for swinging the same in response to changes in temperature, an electric circuit, means causing the pendulum to close said circuit at a predetermined point of its swinging motion, the said means being constructed to clear the path of the pendulum for further swinging motion after the pendulum has acted on the same, and an alarm device disposed for actuation by the pendulum on the continuation of its swinging motion.

6. In combination, heating means, cooling means, a movable element, heat-responsive means for moving the element in response to changes in temperature, means causing the element to render the heating means active at a predetermined minimum temperature and inactive at a higher temperature and means causing the element to render the cooling means active at a predetermined maximum temperature and inactive at a lower temperature.

7. In combination, heating means, cooling means, a movable element, heat-responsive means for moving the element in response to changes in temperature, means causing the element to render the heating means active at a predetermined minimum temperature and inactive at a higher temperature, means causing the element to render the cooling means active at a predetermined maximum temperature and inactive at a lower temperature and an alarm device adapted to be operated by the element when the latter goes beyond a maximum or minimum position.

8. In combination, heating means, cooling means, a movable element, heat-responsive means for moving the element in response to changes in temperature, means causing the element to render the heating means active at a. predetermined minimum temperature and inactive at a higher temperature, means causing the element to render the cooling means active at a predetermined maximum temperature and inactive at a lower temperature and temperature-indicating means associated with the element.

9, In combination, heating means, cooling means, a movable element, heat-responsive means for moving the element in response to changes in temperature, means causing the element to render the heating means active at a predetermined minimum temperature and inactive at a higher temperature, means causing the element to render the cooling means active at a predetermined maximum temperature and inactive at a lower temperature, an alarm device adapted to be operated by the element when the latter'goes' beyond a maximum or minimum position and temperature-indicating means associated with the element.

10. In a thermostat cont-r01, a vertical bar having a pin extending therefrom, a pendulum suspended from the pin, a heat-responsive loop having one end fastened to the bar and having an extension running alongside of the pendulum and a connection between the free end of the extension and the pendulum near its point of suspension causing the pendulum to respond to movements of the loop.

11. In a thermostat control, a pendulum having a contact at its free end, means for suspending the same, heat-responsive means active on the pendulum for swinging the same in response to changes in temperature, a scale mounted in front of the lower end of the endulum and a pointer fastened to the pen ulum and offset therefrom so as to appear in front of the scale.

12. In a, thermostat control, a pendulum having a contactat its free end, means for,

location of parts.

ARNO GRAUE. 

